Serena Williams moved into the third round of the BNP Paribas Open at Indian Wells after seeing off a brave challenge by Victoria Azarenka.
The 23-time grand slam champion prevailed 7-5 6-3 over the Belarusian in their first meeting since the tournament’s 2016 final.
The fellow former world number ones traded four straight breaks in the first set as the rallies grew more intense.
Azarenka had her moments, applying the pressure to hold the American to love in the 10th game, but Williams showed her strength by converting six of her 12 break points.
Williams, who finished with 39 winners, will now face Garbine Muguruza.
"I truly love her, she's a really good friend," 23-times Grand Slam champion Williams said.
"She's a fellow mom and a former number one, just like me.
"It's hard to play someone you're so close with but it's also really invigorating and cool."
The 20th seed had an easier route into the next round, overcoming American wild card Lauren Davis 6-1 6-3.
Second seed Simona Halep also booked her place in the third round with a 6-2 6-4 win over world number 50 Barbora Strycova, but fourth seed Sloane Stephens fell 6-3 6-0 to Switzerland’s Stefanie Voegele.
Britain’s Johanna Konta eased into the third round with a 6-0 6-2 win over 27th seed Su-Wei Hsieh, while other second-round winners included Kiki Bertens, Elise Mertens and Ashleigh Barty.